Genetic Engineering for Disease and Pest Resistance in Plants

Abstract

Huge yield losses and deterioration of quality of cultivated plants have been realized due to continuous exposure of plants to pathogens and insect-pests. The plants and their obligate pathogens and pests have evolved for co-existence. This natural balance has been disturbed by deployment of genes for race-specific vertical resistance and excessive use of pesticides leading to a vicious cycle of emergence of new virulences and search for new genes and potent pesticides. The genetic base for resistance to diseases and insect pests is extremely narrow or does not exist for same plant-pathogen or plant-insect combinations. With the recent advances of cellular and molecular biology and understanding of molecular mechanism of plant-parasite interactions and disease resistance it has been possible to clone, modify and mobilize hitherto inaccesible genes from diverse sources for engineering disease and insect-pest resistant plants. A number of plant species have been successfully transformed for resistance to bacteria, viral, fungal pathogens, nematodes and insects. The transgenic plants have been extensively field tested meeting the stringent biosafety guidelines and released for commercial cultivation since 1990 occupying more than 12 million hectares. Perspectives and strategies for overcoming crucial constraints and concern for engineering high levels of resistance and its exploitation are discussed.